Consider the following equilibrium reaction having gaseous reactants and products.

4HCl + O2 ⇌ 2H2O + Cl2

Which of the following would result from increasing the volume of hydrochloric acid?

The volume of oxygen increases.

The volume of chlorine decreases.

The volume of water vapor increases.

The rate of backward reaction increases.

The volume of water vapor increases.

Explanation:

Pressure, concentration, and temperature all affect the equilibrium position of chemical reactions in a closed system such as this one. Increasing HCl increases the pressure in the system. It favors the forward's reaction because this favors a reduced overall pressure in the system. The products have a combined 3 moles of gases while the reactants have a combined 5 moles of gases.